postProcess

Invoked after the Callable has produced a result in the
async thread in which the Callable is executed. This method may
be invoked later than afterTimeout or afterCompletion
depending on when the Callable finishes processing.

handleTimeout

Invoked from a container thread when the async request times out before
the Callable task completes. Implementations may return a value,
including an Exception, to use instead of the value the
Callable did not return in time.

handleError

Invoked from a container thread when an error occurred while processing
the async request before the Callable task completes.
Implementations may return a value, including an Exception, to
use instead of the value the Callable did not return in time.